Using XBee 900′s for Wildlife Tracking

Urban Range Test Setup

We wanted to find out if XBee 900′s could be used as tracking system. Our first test took place at Washington Square Park. We used two XBee Pro 900 RPSMA. Monkey XBee was fitted with a Digi 2 dBi 7 inch omnidirectional antenna. The trackers XBee was also fitted with the same omnidirectional antenna. One person stayed with the trackers XBee at Washington Square Park, while the other person walked north on Fifth Avenue with the monkey XBee. We were able to get a range of .48 kilometers or 1/3 of a mile with the omnidirectional antennas. We then changed the trackers antenna to a 12 dBi Yagi directional antenna. Using the Yagi antenna increased our distance range marginally. We were able to get an additional .09 kilometers or 300 feet from the Yagi. An increased range was a secondary benefit for us. We used the Yagi antenna mainly to locate the direction of the monkey.

The second was at Central Park. We repeated the first test to see if the trees and foliage changed our results compared to the urban environment of Washington Square Park and Fifth Avenue. The distance range was similar to urban test, the real issue is radio interference. We observed packet loss with the XBee’s. This issue is a characteristic of a highly sophisticated networking protocol. Due to the high radio interference, packets were being resent causing a delay in trying to find the actual direction of the monkey collar. XBee’s are great for getting you data reliably back and forth. However, for our purpose we don’t care for data integrity. We were instead trying to use the XBee’s as radio beacons. Our conclusion was the XBee’s are not a suitable solution for replacing the current analog tracking system.

Taking the advice from Eric Rosenthal I retested the Uniden radio receiver against Tony’s telemetry radio receiver. I setup the Uniden by turning off all the auto features and manually controlling the frequency stepping. I used the good collar which has a frequency of 148.500 MHz. The setting that Eric Rosenthal recommended were set in the first round of testing and remained for this test. The only change was I set the radio to manual mode instead of automatic. The second test mimic the first. I set the collar at a fixed position while I walked away from the collar with the telemetry receiver and the Uniden receiver in my hand. One curious fact that I found in conducting the test was stepping the frequency higher and lower from the base of 148.500 MHz proved to increase the reception of the signal as I increased distance from the collar. I stepped the frequency .1 KHz on the telemetry receiver and I stepped the frequency 10 KHz on the Undien (this is the minimal step increment for the Undien). When I heard the signal dying off I would increment up and down the frequency to improve reception. This was affective for the telemetry receiver but doing the same to the Uniden did not result in a better reception. Both receiver received a clear signal for about 300 feet. After 300 feet the Uniden receiver began to lose the signal as I walked further away. In short the first test that Zeven and I did were accurate. The settings that Eric suggested were indeed what we had configured for the first test.

Our group is in charge of developing a tracking system that improves upon current solutions. The current solution for tracking the monkeys include darting the monkey, putting a radio transmitter collar on the monkey. The observer then tunes in that frequency with a radio receiver and listen for a blip. The hard part is actually telling where the monkey is. The user has to have some skill telling the direction of the blip. Tracking a the monkeys requires using a directional antenna with a radio receiver and listening for faint blips. The user then follows the strongest signal of blips until they can visually see the tagged monkey.

Our group Lisa Maria, Sonaar, Zeven and I want to create a solution that improves upon current technology. For starters, the current receiver require opening the unit up to change the frequency that the receiver listens to. This can be solved by purchasing any radio scanner (receiver). These radio scanners can scan through 50 frequencies a second and can be programmed to remember frequency such as those of the radio collars. These scanners are cheaper than the current receiver which cost around $800. A commercial radio scanner can be purchased for a $100 and have a lot more functionality.

We propose to improve current technology and instruments used to track wildlife. We will look into alternative telemetry receivers, antennas and tagging transmitters. We will test and compare current instruments to different alternatives.